John Dee was a 16th-century astrologer and science advisor to Queen Elizabeth I, but as he got older he became increasingly obsessed with magic. He frequently claimed to contact otherwordly spirits using this black obsidian scrying mirror, currently held by the British Museum.
Circular obsidian mirrors were well-known in Aztec culture and engineering, were used in many spiritual rituals there. Since Europe was awash in artifacts that colonialists had brought back from overseas, historians had long suspected that Dee's scrying-stone was Aztec in origin. But they weren't certain.
Until now. An xray-fluorescence analysis by a team of scientists matched the obsidian in Dee's mirror to obsidian sampled from former Aztec cities, and it looks like Dee's mirror came from Pachua in Mexico.
The team wrote up their findings, and the paper is a fascinating and readable dive into the cultural stew of early colonial voyages. As they write…
When John Dee acquired his mirror, he obtained an unfamiliar and stimulating object, redolent of new and exotic knowledge, which would have been even more unique in an English than in a continental context (Yaya 2008). Given Dee's interest in the New World, he may have been aware of the significance of obsidian, and the omniscience of Tezcatlipoca's mirrors would have had an obvious attraction. Indeed, this may have been a primary reason for its acquisition. He also, however, lived in an era in which the use of mirrors for magical purposes in Europe—particularly black mirrors (Maillet 2004)—meant that the context was receptive to the use of a mirror of exotic origin (Forshaw 2015).
(Thanks to Deb Chacra for pointing this one out!)